This invention relates to a method for manufacturing catalytically active amorphous mixed oxides containing a silica component by the steps of mixing a silica gel with one or more other oxides, extruding the mixture, treating the extrudate with an alkali or alkaline earth base solution at reflux or lower temperature, treating the base solution-treated extrudate by ammonium exchange, and calcining the ammonium-exchanged extrudate.
Inorganic oxides such as alumina or gallia are activated in U.S. Pat. Nos. 4,427,791 and 4,500,418 by contacting same with ammonium fluoride or volatile boron fluoride, followed by contacting with an aqueous ammonium exchange solution.
U.S. Pat. Nos. 4,477,582 and 4,559,131 teach a process for reactivating a catalyst composition comprising a crystalline zeolite having a silicon/aluminum atomic ratio of at least 3.5, the catalyst composition having been deactivated by contact with steam, by contacting the steam-deactivated composition with a metal salt solution, then by contacting with an aqueous ammonium ion-containing solution. Crystalline zeolite ZSM-5 may be the zeolite component of the catalyst composition.
U.S. Pat. Nos. 4,427,789; 4,500,420 and 4,538,016 show a method for enhancing the activity of a crystalline zeolite, including a zeolite having a silica-to-alumina ratio greater than 100, by compositing and extruding the zeolite with an alumina support matrix, vacuum impregnating the extrudate with an aqueous solution of an alkali metal fluoride, contacting the impregnated extrudate with a warm aqueous solution of an ammonium salt and then calcining the final product.
U.S. Pat. No. 4,513,091 teaches a method for introducing tetrahedrally bound aluminum into the structure of a high silica content crystalline zeolite and thereby increasing its acid catalytic activity by forming a mixture of the zeolite and an alumina, and hydrothermally treating the mixture with a dilute aqueous solution of sodium hydroxide at a temperature of about 80.degree. C. to 370.degree. C. and for a time effective to increase the tetrahedrally bound aluminum content of the zeolite. In U.S. Pat. No. 4,478,950, a crystalline high silica-containing zeolite, such as ZSM-5, is hydrothermally treated with aluminate ion to enhance its catalytic activity. U.S. Pat. No. 4,468,475 claims another hydrothermal activation method for enhancing acid catalytic activity of high-silica crystalline zeolite which comprises mixing the zeolite with an activating amount of alumina, and contacting the mixture of zeolite and alumina with an aqueous liquid medium at elevated temperature under conditions to increase catalytic activity of the zeolite.
U.S. Pat. Nos. 4,427,788 and 4,500,422 teach a method for enhancing the activity of a crystalline zeolite, including a zeolite having a silica-to-alumina ratio greater than 100, by impregnating the zeolite with an ammoniacal aluminum fluoride solution, contacting the impregnated zeolite with a warm aqueous solution of an ammonium salt and then calcining the final product.
U.S. Pat. Nos. 4,435,516 and 4,550,092 teach a method for enhancing the acid catalytic activity of a high silica crystalline zeolite having a silica/alumina mole ratio of greater than 500/1 by contacting it with an ammoniacal solution of an alkali metal aluminate for a period of time ranging from 1/2 hour to 5 days at a temperature of from 20.degree. to 50.degree. C. and at pH of at least 10.
U.S. Pat. No. 4,559,315 shows a method for increasing the ion-exchange capacity and acid catalytic activity of a crystalline zeolite by treatment of a physical mixture of the zeolite and an inorganic oxide with water in the presence of an alkali metal cation.
U.S. Pat. No. 4,427,787 the acid catalytic activity of a synthetic crystalline zeolite, including a zeolite having a silica-to-alumina ratio greater than 100, is enhanced by compositing the zeolite with an alumina support matrix and reacting the extrudate thereof with a dilute aqueous solution of hydrogen fluoride.
High alumina content zeolites, such as zeolites X and Y, have been enhanced in catalytic utility by treatment with volatile metal halides, such as aluminum chloride, resulting in ion exchange. This is shown in U.S. Pat. Nos. 3,354,078 and 3,644,220.
Applicants know of no prior art teaching the present invention where amorphous mixed oxides are prepared in catalytically active form.